2 Years ago I was looking for computer speakers and I came across some Labtecs flatpanel speakers, The edge 418's. It's a 2.1 system and goes for around 100 dollars or cheaper.
For the money you get a very nice sound with the character of flatpanel systems like Final or Magnepan.
The sub woofer is very good to, It has some depth wich other sub woofers around this price lack. The only problem is that it can sound a little bit overblown on cheap soundcards.
Labtec stopped producing these speakers, It's worth it looking around for a pair if you want some Hi-Fi sound very cheap. The dearest logitech speakers are crap compared to this
Ps: hook it up to a good cd player and it will really sound like a very expensive system!